feat: Refactor log-alert application into modular structure

- Introduced alerters package with base Alerter class and implementations for LogAlerter and GotifyAlerter.
- Created fetchers package with abstract LogFetcher class and implementations for FileLogFetcher, LokiLogFetcher, and ParseableLogFetcher.
- Added filters package with base Filter class and implementations for RegexpFilter and GeolocationFilter.
- Implemented rules package with base AlertRule class and SimpleAlertRule for alerting logic.
- Enhanced configuration handling with utilities for loading and validating JSON configuration.
- Updated logging setup for better logging management.
- Modified main application logic to utilize the new modular structure, improving maintainability and readability.
- Updated config.json and config.schema.json to reflect changes in alerting and fetching configurations.
- Added python-dateutil to requirements for date parsing functionality.

log-alert/alerters/base.py

@@ -0,0 +1,17 @@
+"""Abstract base class for alerters."""
+
+from abc import ABC, abstractmethod
+
+
+class Alerter(ABC):
+    """Abstract base class for alerting implementations."""
+
+    @abstractmethod
+    def send_alert(self, title: str, message: str) -> None:
+        """Send an alert.
+
+        Args:
+            title: Alert title
+            message: Alert message
+        """
+        pass